In open settings, the participants are autonomous and there is no central authority to ensure the... more In open settings, the participants are autonomous and there is no central authority to ensure the felicity of their interactions. When agents interact in such settings, each relies upon being able to model the trustworthiness of the agents with whom it interacts. Fundamentally, such models must consider the past behavior of the other parties in order to predict their future behavior. Further, it is sensible for the agents to share information via referrals to trustworthy agents. Much progress has recently been made on probabilistic trust models including those that support the aggregation of information from multiple sources. However, current models do not support trust updates, leaving updates to be handled in an ad hoc manner.
Leading agent-based trust models address two important needs. First, they show how an agent may e... more Leading agent-based trust models address two important needs. First, they show how an agent may estimate the trustworthiness of another agent based on prior interactions. Second, they show how agents may share their knowledge in order to cooperatively assess the trustworthiness of others. However, in real-life settings, information relevant to trust is usually obtained piecemeal, not all at once. Unfortunately, the problem of maintaining trust has drawn little attention. Existing approaches handle trust updates in a heuristic, not a principled, manner. This paper builds on a formal model that considers probability and certainty as two dimensions of trust. It proposes a mechanism using which an agent can update the amount of trust it places in other agents on an ongoing basis. This paper shows via simulation that the proposed approach (a) provides accurate estimates of the trustworthiness of agents that change behavior frequently; and (b) captures the dynamic behavior of the agents. This paper includes an evaluation based on a real dataset drawn from Amazon Marketplace, a leading e-commerce site.
Frontiers in Artificial Intelligence and Applications, 2012
This paper is concerned with the combination of argumentation with the Dempster-Shafer theory of ... more This paper is concerned with the combination of argumentation with the Dempster-Shafer theory of evidence. In particular, we show how logical elements of evidence, associated with numerical degrees of belief, can be combined into arguments.
An agent network can be modeled as a directed weighted graph whose vertices represent agents and ... more An agent network can be modeled as a directed weighted graph whose vertices represent agents and edges represent a trust relationship between the agents. This article proposes a new recommendation approach, dubbed LocPat, which can recommend trustworthy agents to a requester in an agent network. We relate the recommendation problem to the graph similarity problem, and define the similarity measurement as a mutually reinforcing relation. We understand an agent as querying an agent network to which it belongs to generate personalized recommendations. We formulate a query into an agent network as a structure graph applied in a personalized manner that reflects the pattern of relationships centered on the requesting agent. We use this pattern as a basis for recommending an agent or object (a vertex in the graph). By calculating the vertex similarity between the agent network and a structure graph, we can produce a recommendation based on similarity scores that reflect both the link structure and the trust values on the edges. Our resulting approach is generic in that it can capture existing network-based approaches merely through the introduction of appropriate structure graphs. We evaluate different structure graphs with respect to two main kinds of settings, namely, social networks and ratings networks. Our experimental results show that our approach provides personalized and flexible recommendations effectively and efficiently based on local information.
Selecting trustworthy service in service-oriented environments
... For example, suppose there is a composed travel service T, which is composed of an underlying... more ... For example, suppose there is a composed travel service T, which is composed of an underlyinghotel service h. If a consumer observes T has reliability 1 at timestep t (ie, xt T = 1) but does not observes the reliability of h, then we can use the expected reliability of h, which is P(h ...
In open settings, the participants are autonomous and there is no central authority to ensure the... more In open settings, the participants are autonomous and there is no central authority to ensure the felicity of their interactions. When agents interact in such settings, each relies upon being able to model the trustworthiness of the agents with whom it interacts. Fundamentally, such models must consider the past behavior of the other parties in order to predict their future behavior. Further, it is sensible for the agents to share information via referrals to trustworthy agents. Much progress has recently been made on probabilistic trust models including those that support the aggregation of information from multiple sources. However, current models do not support trust updates, leaving updates to be handled in an ad hoc manner.
Trust is a crucial basis for interactions among parties in large, open systems. Yet, the scale an... more Trust is a crucial basis for interactions among parties in large, open systems. Yet, the scale and dynamism of such systems make it infeasible for each party to have a direct basis for trusting another party. For this reason, the participants in an open system must share information about trust. However, they should not automatically trust such shared information. This paper studies the problem of propagating trust in multiagent systems. It describes a new algebraic approach, shows some theoretical properties of it, and empirically evaluates it on two social network datasets. This evaluation incorporates a new methodology that involves dealing with opinions in an evidential setting.
Page 1. ICWS 2011 External Reviewers Luciano V. Araújo Aymen Baouab Cristina Baroglio Khalid Belh... more Page 1. ICWS 2011 External Reviewers Luciano V. Araújo Aymen Baouab Cristina Baroglio Khalid Belhajjame Khalid Benali Jiten Bhagat Jeremy Blackburn Kelly R. Braghetto Iris Braun Pavel Bulanov Yan Cai Nicola Calcavecchia Ryan Chard Shiping Chen Hongyu Chen Viktoryia Degeler Juan Du Daniel Dubois Ando Emerencia Hector Fernandez Joshua Finnis Kenneth Fletcher Carsten Friedrich Wei Gao Abhijeet Ghoshal Stephan Gro Heerko Groefsema Gerd Groener Joyce El Haddad Rob Haines Chung-Wei Hang Ferry Hendrikx Julia Hoxha ...
Service selection, where some of the services are accessed indirectly as constituents of composit... more Service selection, where some of the services are accessed indirectly as constituents of composite services, is difficult for the following reasons: (1) the interpretation of service qualities is subjective; (2) evidence must be combined from multiple sources; (3) service profiles change dynamically; and (4) constituent services may be only partially observable behind composite services. We propose an approach where we map service qualities to a common probabilistic trust metric. Whereas current trust approaches estimate the trustworthiness of a composite service based on a fully observable and static setting, we propose a statistical approach built on expectation maximized over a finite mixture model. Our experiments show that our approach can dynamically punish or reward the constituents of composite services while making only partial observations.
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Papers by Chung-wei Hang